diff --git a/src/pretix/static/pretixcontrol/js/ui/main.js b/src/pretix/static/pretixcontrol/js/ui/main.js
index 95b2827a1c..9f3e3ddf6e 100644
--- a/src/pretix/static/pretixcontrol/js/ui/main.js
+++ b/src/pretix/static/pretixcontrol/js/ui/main.js
@@ -277,7 +277,8 @@ var form_handlers = function (el) {
         fill_field.on("dp.show", show);
     });
 
-    function luminanace(r, g, b) {
+    function luminance(r, g, b) {
+        // Algorithm defined as https://www.w3.org/TR/2008/REC-WCAG20-20081211/#relativeluminancedef
         var a = [r, g, b].map(function (v) {
             v /= 255;
             return v <= 0.03928
@@ -287,8 +288,9 @@ var form_handlers = function (el) {
         return a[0] * 0.2126 + a[1] * 0.7152 + a[2] * 0.0722;
     }
     function contrast(rgb1, rgb2) {
-        var l1 = luminanace(rgb1[0], rgb1[1], rgb1[2]) + 0.05,
-             l2 = luminanace(rgb2[0], rgb2[1], rgb2[2]) + 0.05,
+        // Algorithm defined at https://www.w3.org/TR/WCAG20-TECHS/G17.html#G17-tests
+        var l1 = luminance(rgb1[0], rgb1[1], rgb1[2]) + 0.05,
+             l2 = luminance(rgb2[0], rgb2[1], rgb2[2]) + 0.05,
              ratio = l1/l2
         if (l2 > l1) {ratio = 1/ratio}
         return ratio.toFixed(1)
@@ -327,15 +329,15 @@ var form_handlers = function (el) {
         var icon, text, cls;
         if (c > 7) {
             icon = "fa-check-circle";
-            text = gettext('Your color has great contrast and is very easy to read!');
+            text = gettext('Your color has great contrast and will provide excellent accessibility.');
             cls = "text-success";
-        } else if (c > 2.5) {
+        } else if (c > 4.5) {
             icon = "fa-info-circle";
-            text = gettext('Your color has decent contrast and is probably good-enough to read!');
+            text = gettext('Your color has decent contrast and is sufficient for minimum accessibility requirements.');
             cls = "";
         } else {
             icon = "fa-warning";
-            text = gettext('Your color has bad contrast for text on white background, please choose a darker shade.');
+            text = gettext('Your color has insufficient contrast to white. Accessibility of your site will be impacted.');
             cls = "text-danger";
         }
         if ($icon.length === 0) {